Cable impregnating tank



Marh 17, 1964 R. B. YEAKLE 3,125,466

CABLE IMPREGNATING TANK Filed May ll, 1962 2 Sheets-Sheet 1 INVENTOR. ROBERT B. YEAKLE BY wma/WMM ATTORNEYS March 17, 1964 Filed May Il, 1962 R. B. YEAKLE CABLE IMPREGNATING TANK 2 Sheets-Sheet 2 tNVENToR. RoERr B. YEAKLE ,/f" i ATTO/@A1575 United States Patent O 3,125,466 CABLE MPREGNATING TANK Robert li. Yeakle, Scotch Plains, NJ., assigner to General Cable orporation, New York, N.Y., a corporation of New Jersey Filed May l1, 1962, Ser. No. 193,948 5 (laims. (Cl. 118-429) This invention relates to an oil impregnation tank for high-voltage, paper insulated power cables.

in the manufacture of paper insulated, oil impregnated cable, the conductor, consisting of copper strands, is wrapped with a plurality of paper tapes. Gas and water must then be removed from the interstices of the copper strand, from the voids in the paper tape, and from the spaces between the paper tapes. The insulated conductors are then impregnated with =oil which has been previously degassed.

This process has usually been performed in vertical impregnating tanks i.e. cylindrical tanks having the axis thereof disposed vertically. The reels of paper insulated cable are inserted with the reel dlanges horizontal. It is usual to provide a vertical plug concentrically positioned within the tank which plug runs upwardly through the reel hubs. Thus, the volume of oil necessary for impregnation is restricted to the annular space between the plug and the tank, in which space the reels are positioned. In this manner, the volume of processing oil is held to a minimum.

However, with such positioning of the reel (Le. with the flanges horizontal), the cable lay-er adjacent to the lower reel ilange will support the [weight of the cable, causing llattening and/ or deformation of the insulated conductor.

To overcome the difliculties of insulation deformation, the art has used horizontally disposed impregnating tanks. The number of cable layers on each reel can be limited so that the weight thereof w-ill not deform the layer adjacent the drum. The cable may be run in continuous lengths Ion adjacent reels to the capacity of the tank.

To provide access to the tank, tracks Vare usually installed within the tank. Trucks are provided to convey the cable reels in and out of the tank along the tracks. However, by this arrangement, the reels are positioned eccentric to the tank wall. Similarly, a plug through the reel hubs rnust be placed eccentric to the axis of the tank. The eccentricity of the reel to the tank wall'oauses .diiculties in production which were tolerated when small insulated conductors were processed.

Recently, the art has required power cables with higher voltage ratings and larger current carrying capacity. Thus, cables having larger conductors and heavier walls of paper insulation (resulting in an insulated cable of greatly increased outside diameter) are being manufactured. As the diameter of the insulated cable 4is increased, the drum diameter of the takeup reel must be increased to minimize the bending radius of the paper insulated conductor as it is wound onto the reel drum. The drum and, thus, the bending radius, rnust be of suflicient size so as to prevent wrinkling, creasing `or cracking of the tape layers as the insulated lconductor is taken up on the reel. For such purposes, reel drums, 12 ft. or more in diameter, are recommended.

With larger takeup reels, the impregnating tank must be commensurately increased in size. However, the use of pressure vessels of present design of a size to receive the larger reels would require more than a 50% increase in the quantity in impregnating `oil utilized to process the cable. Similarly, the tanks used to degas 'and store processing oil rwould necessarily increase in size to hold the larger quantities of oils needed.

It is, therefore, an object of this invention to provide a horizontal impregnating tank in which the processing lZSAbG Patented Mar. 17, 1964 ice oil volumes may be held to la desirably small quantity for the impregnation of the cable processed therein.

It is a further object lof this invention to provide a horizontal impregnating tank having inner and outer shells in which the inserted reel is positioned concentric to both the inner and outer shells there-of.

In accordance with these objects, there is provided, in a preferred embodiment of this invention, a horizontal impregnating tank comprising an inner cylindrical shell and an outer shell of substantially cylindrical form. The shells :are larranged so as to be concentric about la common axis. The shells are dimensioned to receive the reels with cable wound thereon in the annular space deiined between the inner and outer shells of the tank. The `outer shell is provided with a channel section integrally formed therewith to provide a llat horizontal floor extend-ing axially thereof. The iioor is provided with tracks to receive reel carriages in which cable reels are placed `for movement into and out of the impregnation tank. Thus, when the reel is inserted Within the tank, the concentrioity between the tank shells and the reel is maintained.

At one end of the tank the inner jacket is provided with a dome to seal the inner jacket. At the same end, the outer jacket is provided with a removable door to close the outer jacket, 'leaving a space therebetween for the iiow of impregnating oil. The :other ends of the inner and outer shells are sealedly coupled together.

The tank may be evacuated and heat applied to the paper cable insulation by direct current heat-ing of the cable core. The combination of heating and the vacuum will dry the paper insulation. The inner and outer jackets are provided with steam jacket-s, so that a predetermined cable tempenature may be maintained during both the drying and the impregnating cycles. The concentricity between the tank shells and the cable reels, and the relative closeness between the router shell and reels, are advantageous in maintaining uniform cable temperatures, rapid drying and, thus, a reduction in overall processing time.

The impregnating oil may be admitted to the tank at a predetermined temperature and this temperature held by means of the steam jacketing on both inner and outer shells. Again, the relative closeness between the reels and the shells and the concentricity therebetween provides `a shorter and more uniform path for heat transfer resulting in faster overall processing. The control enabled by the disclosed tank of both cable and impregnating oil ternperatures will permit greater reliability in the nal product and a closer control of the variables encountered in manufacture.

After the cables are impregnated, they must be cooled at a constant rate. Again, the shape of the impregnating tank, particularly the concentricity and the relatively small space between the shell and the reel, will confine the flow of cooled oil closer to the cable, and will provide more uniform conditions the flow of oil and, thus, uniform heat transfer from the cable to the oil. The constant and steady llow of oil over the surface of the cable gives increased efliciency and manufacturing control over the impregnated cable.

Having briey described this invention, it will be described in greater detail in the following portions of the specication which may best be understood by reference to the accompanying drawings, of which:

FIG. 1 is a section-al View taken axially along an impregnating tank constructed in accordance with the instant invention; and

FIG. 2 is a sectional View taken along lines 2--2 of FIG. l.

In the figures, there is shown a horizontal impregnating tank which comprises an inner shell 10 of substantially cylindrical form and an outer shell 12 having a cylindrical section 14 and an integrally formed channel portion 16.

The cylindrical section 14 of the outer shell is disposed in concentric relationship with the inner shell on a cornmon axis. The channel 16 provides a horizontal floor 1S extending axially of the tank upon which floor tracks 20 are mounted. Reel trucks 22 ride on wheels 23 within tracks 20. The trucks are dimensioned to receive the fianges 24 of each reel 25, to support the reel so that its axis is concentric with the axis of the inner and outer shells, and to provide an easy method of loading and emptying the tank.

The inner shell is closed at one end by a dome structure 26. The inner shell is sealedly secured to the outer shell at the other end, as by weld 27. In this manner, the inner shell serves as a plug to occupy the space defined by the hollow hubs of the reels upon which the paper insulated power cable is wound during manufacture. Rigidity of support of the inner sheil is provided by a web plate 28 and anchor strap 30. Thus, an annular space is defined by the cylindrical sections of the inner and outer shells into which the reels with the paper insulated power cables are inserted for processing.

After insertion ofthe reels within the impregnation tank, the tank may be sealed by the closure of the door 34 which is secured to the periphery of the outer shell by bolts 3S and nuts 37' and the fiange fittings 36 and 38. The door is removed by uncoupling the bolts and lifting the door by a crane structure. The crane structure is not illustrated since it is similar to structures known to the art and would unduly complicate the drawings. A peripheral gasket 44 may be provided to ensure a vaportight and oil-tight seal.

In operation, the reels are inserted within the tank, the door 34 closed and bolted in sealed engagement with the tank. The tank is evacuated through the connecting fitting 46. The cable on the reels is heated by the application of direct current to the conductors thereof to dry the paper insulation through the combined effects of the conductor temperature and the evacuation of the tank. The inner shell and outer shell are provided with steam jackets 48 and 50, respectively, which may preferably be formed from panels having integrally-formed steam passages therein, as for example, the panels sold under the trade name Thermopanels by Dean Products, Brooklyn, New York. Alternately, of course, conventional steam coils may be utilized for jacketing of the inner and outer shells. Similarly, dome 26 and door 34 are steam jacketed by coils 51 and 53, respectively.

During drying of the paper insulation, the inner and outer shells are heated by application of steam to the jackets in contact therewith. As opposed to tanks of the construction known to the art, the tank constructed in accordance with the present invention maintains the concentricity between the reels and the inner and outer jackets. In addition to maintaining closer spacing between the cable and the jackets, the concentricity therebetween ensures that the cable will be uniformly heated throughout the periphery thereof. In this manner, uniform cable temperatures may be maintained resulting not only in faster drying, but greater control over product uniformity.

After drying of the cable, impregnating oil is introduced through fitting 52. The impregn-ating oil is introduced from degassing tanks and the oil is heated prior to introduction into the impregnating tank. Oil circulates within the tank through the annular space between the shells and reels and between dome 26 and door 34. During impregnation, the oil is maintained at the desired temperature by control of the steam admitted to jackets f3, 50, 51, 53.

During the impregnation cycle, the close spacing between the shells and reels and the concentricity therebetween provide a short and uniform path for heat transfer from the jackets which results in faster processing i of the cables and allows greater control over the ternperature throughout the entire cable length thereby to result in improved reliability and uniformity of the resultant cable.

After the impregnation cycle is completed, the oil is cooled at a constant rate. ln this operation, as in the impregnation cycle, the concentricity between cable rcel and shells as well as the close and uniform separation therebetween provides a constant and steady flow of oil over the cable surface and permits the maintenance of uniform conditions of oil fiow and heat transfer from the cable to the oil.

Thus, by utilization of a tank constructed in accordance with the present invention, improved control of product uniformity can be maintained and faster processing can be afforded. In addition, the quantities of impregnating oil necessary for this operation are held to a minimum, since the waste space, that is, the space bc- -tween the shell and the jacket is reduced by approximately 20% when contrasted with the impregnating tanks constructed in accordance with the prior art. The reduction in processing oil required allows a concomitant rcduction in the capacity of storage and degassing tanks for the oil.

A further reduction in the quantity of processing oil used may be achieved by constructing the dome 26, door 34 and the enclosure between inner and outer shells as flat plates instead of the dish shaped members illustrated in the preferred embodiment. The fiat plates would, however, increase the tank cost.

After the impregnation and the cooling cycle is completed, the oil may be drained from the tank through fitting 54 and returned to the storage in conventional fashion.

This invention may be variously modified and embodied within the scope of the subjoined claims.

What is claimed is:

1. A horizontal impregnating tank comprising an inner and outer shell, said inner shell being a substantially cylindrical body, said outer shell being formed of a cylindrical body portion and an axially extending U-shaped channel portion, said cylindrical body portion of said outer shell being positioned concentrically with said inner shell, said channel portion being positioned to provide a substantially horizontal floor, said inner and outer shells being sealedly joined at one end thereof, means for sealing the other end of said inner shell, and a door for selectively sealing the other end of said outer shell.

2. A tank according to claim 1 in which said floor is provided with axially disposed tracks.

3. An impregnating tank in accordance with claim 1, which includes steam jackets for heating the surface of the inner and outer shells.

4. An impregnating tank in accordance with claim 1 which includes means for admitting impregnating oil into the annular space between said inner and outer shells and means for removing said impregnating oil from said space.

5. In combination with a tank according to claim 2, wheeled reel carriers engaging said tracks, said reel carriers being adapted to receive reels of cable and to move said reels into the annular space between said inner and outer jackets with said reels being held concentric to the cylindrical surfaces of both said inner and outer jackets.

References Cited in the file of this patent UNITED STATES PATENTS 1,231,007 Fuller June 26, 1917 2,531,156 Piercy etal Nov. 2l, 1950 3,054,382 Ebel Sept. 18, 1962 FOREIGN PATENTS 420,863 Great Britain Dec. 10, 1934 

1. A HORIZONTAL IMPREGNATING TANK COMPRISING AN INNER AND OUTER SHELL, SAID INNER SHELL BEING A SUBSTANTIALLY CYLINDRICAL BODY, SAID OUTER SHELL BEING FORMED OF A CYLINDRICAL BODY PORTION AND AN AXIALLY EXTENDING U-SHAPED CHANNEL PORTION, SAID CYLINDRICAL BODY PORTION OF SAID OUTER SHELL BEING POSITIONED CONCENTRICALLY WITH SAID INNER SHELL, SAID CHANNEL PORTION BEING POSITIONED TO PROVIDE A SUBSTANTIALLY HORIZONTAL FLOOR, SAID INNER AND OUTER SHELLS BEING SEALEDLY JOINED AT ONE END THEREOF, MEANS FOR SEALING THE OTHER END OF SAID INNER SHELL, AND A DOOR FOR SELECTIVELY SEALING THE OTHER END OF SAID OUTER SHELL. 